Featured Torque curves - Shimano, Bosch, Brose, Yamaha

100 Cols

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#1
This is not Shimano related post, but couldn't find a better place for posting, so here we go.

I found power curves of few motors from the electricbikereview.com and did some "reverse engineering" to visualize also the torque curves (something I've not seen before). I was interested in torque, because when climbing, torque is usually more relevant than max power and also because I was frustrated of reading manufacturer torque claims without any reference to corresponding crank rpm.

Some of you might be interested in this, too:

torque-reverse-engineered-png.1352


The original power chart looks like this:
powers-jpg.1356


Flame on.
 

Rob Hancill

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#2
Interesting. I wonder how accurate that source data is though?
 

ccrdave

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#3
is that specialised brose or another brand? in my experience the brose motor in other brands performs very different from the specialised tune
 

Kernow

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#4
Interesting but I don’t understand the high torque at low rpm ,on the top graph , my shimano feels dead below 60 rpm as it should I think
the power diagram describes how the motors I’ve tried felt to my legs , but they all feel so different depending on which setting is used , and surely the curve for the trail or middle adaptive modes is going to be way different to the full boost setting , ?
I think that unless you have spent a little time working on your cadence it’s all a lot more difficult to understand ,
 

100 Cols

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#5
Source data was probably "leaked" from Bosch without any reference to the measurement method, so accuracy is pretty much unknown. However, it seems that calculated torque (out of those power curves) actually corresponds pretty well to the claimed torque figures (with the exception of Brose):

- Bosch Performance Line: 63 Nm claimed, vs. 63.5 Nm @35 rpm calculated
- Bosch CX: 75 Nm claimed, vs. 74.6 Nm @45 rpm calculated
- Shimano E8000: 70 Nm claimed, vs. 69.5 Nm @35 rpm calculated
- Brose: 90 Nm claimed, vs. 74.2 Nm @20 rpm calculated
- Yamaha: 70 Nm claimed, vs. 70.1Nm @25 rpm calculated

I should have said in the previous post that the torque charts above are "polynomially smoothed"
 

Rob Hancill

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#6
I bet that Brose was the old 1.2 motor as the source info was posted in July 17 (and likely tested much earlier than that). That would have been before the Brose 1.3 motor was released.
 

100 Cols

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#7
Interesting but I don’t understand the high torque at low rpm ,on the top graph , my shimano feels dead below 60 rpm as it should I think
AFAIK, that's how electric motors generally behave, their torque goes down when they approach their max angular speed. Also, power and torque are directly related, if you know power and angular velocity (rpm), you can calculate the torque. And vice versa.

surely the curve for the trail or middle adaptive modes is going to be way different to the full boost setting , ?
Yes, of course.

I think that unless you have spent a little time working on your cadence it’s all a lot more difficult to understand ,
I'm afraid I don't understand this. I have spent _years_ working on my cadence.
 

Kernow

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#8
I'm afraid I don't understand this. I have spent _years_ working on my cadence.
Sorry I didn’t make that comment very clear What I mean is unless a rider knows ie has counted / checked cadence somehow it’s harder to get a feel of what the graph means , if you know your cadence averages say 80 rpm it’s easier to read the info and see where each motor will work best for a person
It’s a good interesting thread
 

Gary

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#9
I have spent _years_ working on my cadence.
What do you mean by "working" on it?
It takes very little time to train your body to reach higher peak max cadences. and not very long at all to raise your sustainable (comfortable) high end cadence.
Mine are both well above average from nothing more than boredom and having a Garmin Cadence sensor fitted to my roadbike
 

100 Cols

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#10
What do you mean by "working" on it?
It takes very little time to train your body to reach higher peak max cadences. and not very long at all to raise your sustainable (comfortable) high end cadence.
Wow! I'm amazed that you think you know my body or how long it took me to re-learn to pedal at high cadences. That's quite a big headed claim there.

With working on it, I mean that after two strokes I've had (2007, 2014), I've had to re-learn walking, coordination, keeping balance and finally cycling and then higher cadences. It took more than "very little time", actually it has taken years, no matter what you claim.

Mine are both well above average from nothing more than boredom and having a Garmin Cadence sensor fitted to my roadbike
Cool. You're the man.
 

Gary

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#11
Sorry man. I misunderstood what you were saying completely :oops:

all I meant was improving rpm is much more to do with practice and honing a smooth pedalling action than "working" harder.
 

Kernow

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#13
Never had cadence reading on a mtb before , off road up and down humps and bumps combined with the ebikes power assistance make it harder to stay in a good range , it’s much easier to suddenly get too fast or slow down when your not working too hard An above average cadence really works against you with the motors limit
 

Kernow

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#14
since owning my Emtb one thing I've struggled to work out is exactly how cadence effects asistance with my Shimano motor betwen the various modes. Although I will say since the update I did a couple of days ago it all feels markedly more intuitive and far more useful than it was stock.
It takes a while to get the hang of it for sure , and that initial puppy dog reaction to go everywhere in boost doesn’t help . I found using trail and riding up short but steep climbs is a good way to get used to it .
 

Japuserid

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#15
What a brilliant bit of work and looking at the torque graph especially I really think it's not far from the mark at all. I had the CX for 2 years, undoubtedly the strongest of the bunch, Been riding the E8000 for a couple of months, was initially a little disappointing compared to the CX but only a little and now beginning to love it's more subtle nature. Limited experience of the Yamaha but swapped with a mate for an hour, strong at the bottom but run's out of puff a bit too early and the Levo I tried with the old Brose 1.2 was just, sorry to say very weak. The original source material was dated July 2017 so would be very interested to see how the newer 1.3 Brose compares? Very much improved by all accounts, but as the graph show's it would need to be.
 

kcarbon

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#16
From experience with Dyno's & riding & racing motor bikes. the only chart we need to look at is the Torque curve, as with MC's that is all I really feel, the power I can't really feel that it mostly shows up in higher speed ( I can feel the speed!! but the torque is what you feel being thrust forward )
all over I am very happy with the bike I have, it does everything I ask, and if I want more,.... I just peddle harder.
cheers , interesting thread
 
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#17
Great analysis. I've ridden all but the Shimano and couldn't "feel" the differences as well as some have articulated; guess I'm too stoic. However, this explains why my SDURO signs off the way it does.
 

Jackware

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#18
Bumping an old thread :unsure:
How does Bosch CX motor speed relate to the pedaling cadence, as I know the chainring/sprocket spins at 2.5 times that of the pedaled crank but I'm guessing there's further gearing inside looking at exploded diagrams of the motor?
TL:DR what's the ideal pedaling cadence to get the 60-80rpm CX motor's sweetspot?
 

kcarbon

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#19
looking at the chart must be misleading, as my friend has a 12017 Levo HT & a guy with a Shimano powered FSR bike higher spec that the LEVO HT, was saying how fast his bike was and that he does not get enough of a work out. then on return ride my friend on LEVO HT road hard he is a good rider and was over the speed that motor gives assistance the Shimano powered Guy could not keep up and was asking my friend " what have you done to make your bike so fast? " I was laughing when my friend told me because he has never owned a mobile phone let alone a smart phone to make any tune adjustments. but when they are over the assistance speed, it's the rider that powers the bike.
 

R120

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#20
I have both a FS and HT Shimano Steps motored bike, and the HT is a faster accelerating/feeling bike on smooth terrain, and even up until you get to really technical terrain where getting bounced around takes its toll. Basically because it is a HT and has no power loss through the suspension.
 

Kiwi in Wales

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#21
I just had another look at the table.
Very interesting reading......
I am really not sure where these figures came from though..... According to the information that I have actually measured myself and gathered on the 2017 1.2 Levo motor and the 2018 1.3 Levo motor the figures below in the table are way out.

One of the great things about the Levo is the amount of data that can be captured whilst riding using either the MC (Mission Control) App or the Blevo App.

I have constantly measured around 650-670 Watts on my 2017 1.2 motor Levo using both Apps so I would say these measurements ‘should’ be fairly accurate? as both Apps were within 10 Watts of each other when the outputs were captured at virtually the same time.

I also got a number of the forum members to send me their captured Motor Power outputs on their 2018 1.3 motor Levo’s and a number of them averaged between the 740 and 780W mark which to me makes sense as the 2018 Levo was supposed to be around 15% more powerful.

As you can see, comparing the Brose figures in the table below with my figures above appears to show a very large discrepancy. 350 v 670 v 780 ?

0acc5a2d-814c-4696-b53a-b54a1b297032-jpeg.7268


However, some very recent 1.3 Levo motors that I have have measured have only been putting out 570-590W? Only....?
The only thing I can think of regarding this low 570-590W output is maybe the motors have been detuned to come in line with the other manufacturers figures? Or maybe they detuned them to reduce warranty claims?

What are your thoughts all?
 

steve_sordy

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#22
Hello, newbie here contemplating my first eBike. I found this thread very interesting, but also confusing. Newbie question coming!

I thought eBike motors were restricted to 250W output, yet the charts above, and the subsequent posts, all refer to considerably more than that. I'm assuming that there is an answer that will make me cringe with its simplicity. :rolleyes:
 

Kernow

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#23
I just had another look at the table.
Very interesting reading......
I am really not sure where these figures came from though..... According to the information that I have actually measured myself and gathered on the 2017 1.2 Levo motor and the 2018 1.3 Levo motor the figures below in the table are way out.

One of the great things about the Levo is the amount of data that can be captured whilst riding using either the MC (Mission Control) App or the Blevo App.

I have constantly measured around 650-670 Watts on my 2017 1.2 motor Levo using both Apps so I would say these measurements ‘should’ be fairly accurate? as both Apps were within 10 Watts of each other when the outputs were captured at virtually the same time.

I also got a number of the forum members to send me their captured Motor Power outputs on their 2018 1.3 motor Levo’s and a number of them averaged between the 740 and 780W mark which to me makes sense as the 2018 Levo was supposed to be around 15% more powerful.

As you can see, comparing the Brose figures in the table below with my figures above appears to show a very large discrepancy. 350 v 670 v 780 ?

View attachment 7268

However, some very recent 1.3 Levo motors that I have have measured have only been putting out 570-590W? Only....?
The only thing I can think of regarding this low 570-590W output is maybe the motors have been detuned to come in line with the other manufacturers figures? Or maybe they detuned them to reduce warranty claims?

What are your thoughts all?
Certainly the demmo Levo I had for week felt like that graph shows compared to the Bosch I was comparing with , and subsequently bought shimano . I wondered if my demmo had been de tuned as I understand they shred belts with heavy riders aboard , but that’s surely not going to secure a sale so easily ? , but others Levi’s I’ve come across since are the same compared to the other motors . As is asked here I don’t understand this power figure of 500plus w that’s being talked about fir a 250 w motor
 

100 Cols

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#25
The original data (the power graph) is quite old, which means that most probably the Brose motor there is older generation, before 1.2.
 

knut7

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#26
So this is
Bosch Performance (discontinued i believe)
Bosch Performance CX
Shimano Steps E8000 (this graph was released may/jun 2017, probably pre-production firmware)
Yamaha PW (discontinued)
Brose (old discontinued model)

Not very relevant any more.
 

steve_sordy

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#27
250W is a "nominal" power designation. -- continuous power a motor system can put out indefinitely. The graph is comparing peak power.
OK, got that. Thanks.
So for how long can this peak power be drawn upon before something happens (overheating, power shutdown, battery damage....)? Is a chart showing peak power even useful?
 

100 Cols

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#28
Is a chart showing peak power even useful?
That is a good question. For me personally, it is much more useful than "fan boy stories" or manufacturer's "one figure" torque claims (e.g. 90 Nm without any reference to rpm range or anything. But of course, the whole truth is not in these charts, which, in addition, are unfortunately outdated.

I sense more comprehensive independent motor analysis ahead.
 

100 Cols

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#29
So this is
Bosch Performance (discontinued i believe)
Bosch Performance CX
Shimano Steps E8000 (this graph was released may/jun 2017, probably pre-production firmware)
Yamaha PW (discontinued)
Brose (old discontinued model)

Not very relevant any more.
At least Shimano and CX are still valid. I have not been following Bosch news too actively, but actually Bosch Performance is still visible on their website, too.

Will be back.
 

steve_sordy

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#30
Car manufacturers have shown torque and power curves across the rev range for decades. That seems to have stood the test of time.

I always understood that the power shown was the continuous power available at the rpm shown, not the peak power.

But of course the big difference is that the power unit there is an internal combustion engine and not a battery, which is a markedly different power source. So what does Tesla do?
 

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